Review Reports

Round 1

Reviewer 1 Report

In this paper, the authors investigated the properties of lignin modified bitumen. It was found that lignin powder could harden the conventional bitumen. Specifically, the addition of 15% lignin to the bitumen hardened the blend to such a degree that the bitumen changed category from 50/70 to 35/50. This work has certain value for asphalt modification research.

(1) In Abstract, the authors need to express the aim of this work directly in the beginning sentences.

(2) In Fig.2, the TG curve need to re-tested. As lignin is a bio-polymer, the TGA is not correct.

(3) Although the thermal stability of lignin is tested, the stability of lignin in bitumen is still necessary.

(4) The dispersion uniformity of lignin in bitumen needs to be considered.

(5) The expression of conclusion is too long and needs to be simplified.

(6) In Fig.10-13, error bars should be added in data.

Author Response

We thank Reviewer 1 for his valuable comments. We have uploaded our responses to the MS word file 'Answer to Reviewer 1'.

Author Response File: Author Response.docx

Reviewer 2 Report

The current study looks at the properties of lignin modified bitumen. This is not a completely new topic but it a novel one at this time. However, the presentation and analysis level in this work fall short of what is needed for a journal publication. Specific comments below.

 

Many figures are poor in quality, please review. Surprised the journal let this through like this.

 

Reference to both "Kraft" and "Craft" lignin. It should be Kraft as it is a reference to the Kraft method for processing pulp.

 

Fig 1 - all that can be see is the power with no scale, how is this the "macrostructure"?

 

L130 - no description of where the elemental analysis comes from.

 

While the tests show that there was improvement of the bitumen properties with lignin, no attempt is made to discuss the reasons for this.

Author Response

We thank Reviewer 2 for his/her valuable comments. We have uploaded our responses to the MS word file 'Answer to Reviewer 2'.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

This manuscript can be accepted.

Reviewer 2 Report

The original reviewer comments have been minimally addressed. The significant problems in lack of analysis and presentation remain and there for I must recommend rejection.